Pouch battery with safety protection function

ABSTRACT

A pouch battery contains a pouch, an electrode material and a safety protection device. The electrode material is located in the pouch. The safety protection device is configured to generate an action based on a change in gas pressure within the pouch. In this way, even if the pouch battery is abnormal, its internal circuit can be cut off in time to avoid providing power to external devices while being under abnormal conditions.

FIELD OF THE DISCLOSURE

The invention relates to a pouch battery, and more particularly to safety issues associated with pouch batteries.

BACKGROUND

The biggest difference between a pouch battery and a conventional steel-case or aluminum-case battery is that the pouch battery is made of a pouch material (plastic-aluminum composite film). This makes the pouch battery have the following advantages: light weight, compact dimension, flexible design, and arbitrary variation of the shape. Also, in the event of a safety issue, the pouch battery typically cracks, unlike an explosion in the case of a steel-case or aluminum-case battery.

However, although pouch batteries generally do not explode, because they do not have the protection from a similar hard case (steel case/aluminum case), the damaged pouch may cause expanded gas to be ejected from the pouch. At the same time, if the pouch battery still provides power to devices that are powered by the pouch battery, such as other components inside a power tool, this may pose a safety hazard.

SUMMARY

Therefore, there is a need for a technical solution which can further improve the safety of a pouch battery.

Embodiments of the present invention provide a pouch battery including a pouch, an electrode material located in the pouch, and a safety protection device. The safety protection device is configured to generate an action based on a change in gas pressure within the pouch.

In a specific embodiment, the pouch battery further includes an anode tab and a cathode tab. The anode tab and the cathode tab extend from the pouch. The safety protection device includes a circuit cut-off device. At least one of the anode tab and the cathode tab is connected to the electrode material by a circuit cut-off device.

Preferably, the circuit cut-off device is a circuit breaker. The circuit breaker is configured to cut off the electrical connection between at least one of the anode tab and the cathode tab, and the electrode material, when the gas pressure in the pouch reaches a predetermined value due to the gas expansion.

More preferably, the circuit breaker is configured to be mechanically separated into two parts, so as to cut off the electrical connection between at least one of the anode tab and the cathode tab, and the electrode material, when the pressure in the pouch reaches the predetermined value due to the gas expansion.

In another specific embodiment, the safety protection device includes: a pressure sensor; a controller connected to the pressure sensor; and an actuator connected to the controller. The actuator is configured to perform a safety action when receiving a control signal sent by the controller based on the gas pressure in the pouch detected by the pressure sensor which reaches a predetermined value due to gas expansion.

In a variable embodiment, the actuator is an alarm. The alarm is configured to send an alert to a user based on the control signal.

In another variable embodiment, the actuator is a switch. The switch is configured to cut off the electrical connection between at least one of the anode tab and the cathode tab and the electrode material in accordance with the control signal.

The invention provides corresponding safety protection mechanisms based on expansion characteristics of the pouch battery under high temperature or overcharge condition. Such expansion characteristics specifically refer to an increase in volume of the gas contained in a pouch battery due to a change in temperature resulted from a high temperature or overcharge. The change in gas volume results in an increase in the pressure within the fixed volume within the pouch, and such pressure can be used to cut off the circuit, thereby interrupting the internal circuit of the pouch battery. In this way, even if the pouch battery is abnormal, its internal circuit can be cut off in time to avoid providing power to external devices under abnormal conditions. This safety protection mechanism is completely built into the pouch battery and does not require any additional components to be arranged outside the pouch battery. Therefore, the pouch battery of the present invention can exerts its safety function regardless of how the electronic device is mounted without being bound by the electronic device. In addition to cutting off the circuit, the pouch battery of the present invention can also be configured to provide an alert to the user so that the user can know the abnormality of the pouch battery and eliminate the condition in time.

BRIEF DESCRIPTION OF THE DRAWINGS

The performance and advantages of the present invention can be further understood by reference to the remaining part of the specification and the accompanying drawings; in the drawings, the reference signs of the same components are the same. In some cases, a sub-label is placed after a label and hyphen to represent one of many similar components. When referring to a label but not specifically stating an existing sub-label, it refers to all of these similar components.

FIG. 1 is a schematic view showing the appearance of a pouch battery according to a first embodiment of the present invention.

FIG. 2a is a schematic view showing the structure of the interior of the pouch battery of FIG. 1, in which the circuit breaker is not separated.

FIG. 2b is a schematic view showing the structure of the interior of the pouch battery of FIG. 1, in which the circuit breaker is disconnected due to the expansion effect.

FIG. 3 is a perspective view of the inner component of the pouch battery after its pouch is removed, in accordance with another embodiment of the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

In the embodiments of the invention, the circuit inside the pouch battery may be automatically cut off according to the expansion effect of the pouch battery resulted from high temperature or overcharge, thereby preventing the occurrence of an accident. Other different benefits and advantages provided by the various embodiments of the present invention are readily apparent from the following description.

Turning first to FIG. 1, there is shown the appearance of a pouch battery 22 in accordance with a first embodiment of the present invention. The pouch battery 22 includes a pouch 26 as its outer shell having a substantially rectangular shape. A front end 28 of the pouch 26 is formed by cutting and folding the pouch material. The pouch 26 is, for example, a plastic aluminum packaging film. The anode tab and a cathode tabs 20, 24 respectively extend from the front end 28 to facilitate connecting the pouch battery 22 to other external devices (not shown), such as a power tool. Above structure of the pouch battery 22 is well known to those skilled in the art and will not be described herein.

Now turning to FIGS. 2a-2b . It can be seen that electrode material 34 is received in the pouch 26 of the pouch battery 22 described above. As is well known to those skilled in the art, the electrode material 34 includes an anode material, a cathode material, a separator, and the like (all are not shown). Between the electrode material 34 and the inner surface of the pouch 26, a gap 32 is present in at least a portion of the area of the pouch 26. The gas generated in the formation step in the production process of the pouch battery 22 exists in the gap 32. The electrode material is connected to the anode tab and a cathode tabs of the pouch battery 22. For the clarity of illustration, only the anode tab 20 is shown in FIGS. 2a and 2b , and the cathode tab is not shown. The anode tab 20 has an end extending beyond the pouch 26 as described above, specifically beyond the front end 28 of the pouch 26. The anode tab 20 is held by the front end 28 by the tab-film 36 near the front end 28 of the pouch 26. As shown in FIG. 2a , the other end of the anode tab 20 inside the pouch 26 (i.e., the end remote from the front end 28 of the pouch 26) is secured to the electrode material 34 by adhesive 38 which is electrically conductive. One surface of the other end of the anode tab 20 is bonded to the electrode material 34, and the other surface is connected to the inner surface of the pouch 26 by welding or the like. The anode tab 20 and the adhesive 38 described above together constitute the safety protection device of the present embodiment, and specifically constitute a circuit breaker.

Now we will see how the safety protection function of the above-mentioned pouch battery 22 works. FIG. 2 shows a state when the pouch battery 22 is operating normally. At this time, the pouch battery 22 does not generate high temperature or is overcharged, therefore the gas in the internal space 32 of the pouch 26 does not expand. Therefore, the circuit breaker of the pouch battery 22 is in an ON state and is not disconnected. As can be seen in FIG. 2a , the adhesive 38 connects the anode tab 20 to the electrode material 34 and there is an electrical connection between them. On the other hand, the anode tab 20 is also fixedly connected to the inner surface of the pouch 26. If the pouch battery 22 is subjected to high temperature or overcharge, the gas in the inner space 32 of the pouch 26 expands. This is also known as the expansion effect. The expansion of the gas causes its volume to increase and pressure is exerted on the boundary of the internal space 32. Such pressure causes the pouch 26 to deform because the pouch 26 is made of a kind of material that can be easily bent. If the pouch 26 on one side of the inner space 32 is deformed, the distance between this portion of the pouch 26 and the electrode material 34 on the other side of the inner space 32 is increased, which may cause a pulling force on the above-mentioned circuit breaker. In particular, such a pulling force results in the adhesive 38 no longer being sufficient to maintain the bonding between the electrode material 34 and the anode tab 20, which would separate the two. This is most clearly shown in FIG. 2b . Since the electrode material 34 and the anode tab 20 are no longer connected together, the electrical connection between them is also interrupted at the same time. This causes the pouch battery 22 to no longer externally output power, thereby ensuring the safety of the electric equipment.

Now turning to FIG. 3. A pouch battery 122 according to another embodiment of the present invention includes a circuit board 122 and an electrode material 134. A controller 136 and an actuator 138 are mounted on the circuit board 122. One end of the pressure sensor 142 is located between different layers in the electrode material 134, and the other end of the pressure sensor 142 is connected to the controller 136. Therefore, the pressure sensor 142 can provide the sensed pressure data inside the pouch battery 122 to the controller 136. The actuator 138 may be an alarm that gives a visual or audible alarm to the users, or a switch that may cut off the internal circuit of the pouch battery 122. The controller 136, the actuator 138, and the pressure sensor described above constitute the safety protection device in this embodiment.

During use, if the pouch battery 122 does not generate high temperature or overcharge, the gas inside the pouch battery 122 does not expand. Therefore, the pressure sensor 142 does not detect a pressure abnormality, and the controller 136 does not control the actuator 138 to perform any action. If the pouch battery 122 is subjected to high temperature or is overcharged, the gar expansion inside thereof causes the gas volume to increase and pressure is generated. Such pressure creates squeezing on the pressure sensor 142, and the detected real-time pressure data is provided to the controller 136 by the pressure sensors

Having thus described several embodiments, those skilled in the art will recognize that various modifications, other structures, and equivalents may be used without departing from the spirit of the invention. Accordingly, the above description should not be taken as a limitation to the protection scope of the invention as defined by the following claims.

For example, the safety protection device described in the above embodiment may be a circuit breaker, or an actuator controlled by a controller on a circuit board or the like. However, those skilled in the art will appreciate that other types of safety protection devices may also fall within the scope of the present invention, as long as such safety protection devices are capable of performing corresponding protection actions based on the gas pressure inside the pouch battery.

In addition, only the circuit breaker to which the anode tab is connected is shown in the pouch battery 22 illustrated in FIGS. 2a-2b . However, it needs to be understood that this does not mean that only the anode tab may be connected to the circuit breaker. Conversely, only the cathode tab may be connected to the circuit breaker in the pouch battery, or the anode and cathode tab can be connected to their respective circuit breakers at the same time. Such designs can be varied by one skilled in the art in light of the specific design requirements. 

What is claimed is:
 1. A pouch battery comprising: a pouch; an electrode material located in the pouch; and a safety protection device, the safety protection device including: a controller configured to send a control signal in response to a gas pressure within the pouch reaching a predetermined pressure, and an actuator configured to: receive the control signal from the controller, and upon receiving the control signal, disconnect an electrical connection between the electrode material and at least one selected from a group consisting of an anode tab and a cathode tab, wherein the actuator includes an alarm configured to provide an alert to a user based on the control signal.
 2. The pouch battery according to claim 1, further comprising an anode tab extending from the pouch and a cathode tab extending from the pouch; wherein the safety protection device includes a circuit cut-off device configured to connect the electrode material and at least one of the anode tab and the cathode tab.
 3. The pouch battery according to claim 2, wherein the circuit cut-off device includes a circuit breaker configured to cut off an electrical connection between the electrode material and the at least one of the anode tab and the cathode tab in response to the gas pressure in the pouch reaching a predetermined pressure due to gas expansion.
 4. The pouch battery according to claim 3, wherein the circuit breaker is configured to be mechanically separated into two parts to cut off the electrical connection between the electrode material and the at least one of the anode tab and the cathode tab in response to the gas pressure in the pouch reaching the predetermined pressure due to the gas expansion.
 5. The pouch battery according to claim 1, wherein the safety protection device comprises: a pressure sensor connected to the controller configured to detect the gas pressure within the pouch. 